Surface ¹⁴N abundance as a function of stellar age of our model 20 M_⊙ star with initial equatorial rotational velocity of 300 km s^-1. Rotational mixing coefficients are calculated without any inhibitance of the mean molecular weight gradient. Models sequences have a 0.05 M_⊙ fixed shell mass with various timesteps in Myr by BONNFIRES. The surface nitrogen enhancements are similar for model sequences with all timesteps from 0.001 Myr to 0.1 Myr.